Pertussis is a respiratory disease caused by bacteria that grow only on the ciliated epithelium of the respiratory tract. We are currently studying the cells involved in vaccine-mediated immunity in the respiratory tract in a mouse model of respiratory infection. We have found that the form of vaccine antigens as well as the site of immunization markedly change the kind of immune response observed . Acellular vaccine antigens, in soluble or particulate form, stimulate an antibody response and reduce infection when given by either a respiratory or a parenteral route. A whole cell vaccine, composed of formalinized B. pertussis, stimulates an antibody response when given by a parenteral route, but not by a respiratory route, and yet is highly protective against infection when given by the respiratory route; this protection requires mature T cells, as nude mice are not protected. Populations of T cells that proliferate specifically in response to antigen and secrete cytokines are generated in the draining lymph nodes of the lungs of mice immunized intranasally with either form of pertussis vaccine. We are currently establishing T cell lines and T cell clones from vaccinated mice. Established mouse T cell clones to pertussis vaccine antigens will allow us to study in a detailed fashion, the role of T cells in protective respiratory immunity to B. pertussis infection.